Air bubbler to increase glass production rate

Abstract

In a glass melter, a precious metal insert is used to protect a gas bubbler from corrosion at the orifice of the bubbler through which gas is injected into the melt. The use of a precious refractory metal insert at the bubbler orifice prevents the attack of molten glass on the bubbler. The precious metal is chosen from the refractory group of metals and the platinum group of metals. Preferably the precious metal from the platinum group is platinum or one of its alloys or one of ruthenium, rhodium, palladium, osmium and iridium. The precious metal from the refractory group is preferably chromium.

We claim:  
     
       1. A joule-heated melting furnace for the inertization of hazardous substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank, said gas bubbler being an electrode connected to a power supply,  
       a gas outlet of said gas bubbler, and  
       a precious metal insert of said gas bubbler, said gas outlet extending through said precious metal insert for release of the gas into said tank.  
     
     
       2. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 1 , wherein said precious metal insert is made of platinum. 
     
     
       3. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 1 , wherein said precious metal insert is made of a platinum alloy. 
     
     
       4. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 1 , wherein said gas bubbler includes a gas supply pipe, said gas supply pipe extending from above a level of a glass melt into the glass melt. 
     
     
       5. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 1 , wherein said gas bubbler includes a gas supply pipe extending through a side wall of the tank. 
     
     
       6. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 5 , wherein said gas supply pipe is lined with an internal protective liner. 
     
     
       7. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 6 , wherein said protective liner is mullite. 
     
     
       8. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 4 , wherein said gas supply pipe includes a protective sleeve at the level of the glass melt. 
     
     
       9. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 8 , wherein an annular gap is formed between said protective sleeve and said gas supply pipe. 
     
     
       10. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 9 , wherein said annular gap includes one of magnesium oxide powder and mullite. 
     
     
       11. A joule-heated melting furnace for the inertization of hazardous substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls, and  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank, said gas bubbler being connected to a power supply for use of the gas bubbler as an electrode in the tank.  
     
     
       12. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 11 , wherein said gas bubbler extends through a side wall of the tank. 
     
     
       13. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 12 , wherein said gas bubbler is lined with an internal protective liner. 
     
     
       14. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 13 , wherein said protective liner is mullite. 
     
     
       15. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 11 , wherein said gas bubbler includes at least one bubbler hole. 
     
     
       16. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 15 , wherein each bubbler hole is connected to a separately controlled gas supply. 
     
     
       17. A joule-heated melting furnace for the inertization of hazardous substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank, said gas bubbler being an electrode connected to a power supply, and  
       a gas supply pipe extending through a side wall of the tank and connected to said gas bubbler, said gas supply pipe being lined with an internal protective liner for preventing formation of scales in said gas supply pipe.  
     
     
       18. A joule-heated melting furnace for the inertization of hazardous substances as claimed in  claim 17 , wherein said protective liner is mullite. 
     
     
       19. A joule-heated melting furnace for the inertization of radioactive substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls suitable for containing radioactive substances,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank,  
       said gas bubbler including a gas supply pipe, said gas supply pipe extending from above a level of a glass melt into the glass melt,  
       a protective sleeve surrounding said gas supply pipe at the level of the glass melt with the protective sleeve being-fixed to the gas supply pipe, and  
       an annular gap formed between said protective sleeve and said gas supply pipe.  
     
     
       20. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 19 , wherein said annular gap includes magnesium oxide powder. 
     
     
       21. A process to stir a glass melt containing hazardous substances in a melting furnace, said process comprising: 
       inserting a gas bubbler into the glass melt above a bottom wall of a tank containing the glass melt,  
       passing a gas into the gas bubbler, and  
       introducing the gas into the glass melt through an orifice formed in a precious metal insert of the gas bubbler,  
       passing an electric current into the glass melt through the gas bubbler.  
     
     
       22. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein said precious metal insert is made of platinum. 
     
     
       23. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein said precious metal insert is made of a platinum alloy. 
     
     
       24. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein said gas bubbler is inserted into the glass melt from above the glass melt. 
     
     
       25. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein said gas bubbler is inserted into the glass melt through a side wall of the tank containing the glass melt. 
     
     
       26. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein said gas bubbler is inserted into said glass melt until a protective sleeve of said glass bubbler is located at an upper level of said glass melt. 
     
     
       27. A process to stir a glass melt containing hazardous substances as claimed in  claim 21 , wherein a protective liner is inserted into said gas bubbler to prevent production of scaling in said gas bubbler from being introduced to said orifice. 
     
     
       28. A joule-heated melting furnace for the inertization of radioactive substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls suitable for containing radioactive substances,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank,  
       a gas outlet of said gas bubbler,  
       a precious metal insert of said gas bubbler, said gas outlet extending through said precious metal insert for release of the gas into said tank,  
       said gas bubbler including a gas supply pipe, said gas supply pipe extending from above a level of a glass melt into the glass melt,  
       said gas supply pipe including a protective sleeve at the level of the glass melt with the protective sleeve being fixed to the gas supply pipe, and  
       an annular gap formed between said protective sleeve and said gas supply pipe.  
     
     
       29. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 28 , wherein said annular gap includes one of magnesium oxide powder and mullite. 
     
     
       30. A joule-heated melting furnace for the inertization of radioactive substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls suitable for containing radioactive substances,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank,  
       a gas outlet of said gas bubbler,  
       a metal insert of said gas bubbler made of chromium, said gas outlet extending through said metal insert for release of the gas into said tank,  
       said gas bubbler including a gas supply pipe, said gas supply pipe extending from above a level of a glass melt into the glass melt,  
       said gas supply pipe including a protective sleeve at the level of the glass melt with the protective sleeve being fixed to the gas supply pipe, and  
       an annular gap formed between said protective sleeve and said gas supply pipe.  
     
     
       31. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 30 , wherein said annular gap includes one of magnesium oxide powder and mullite. 
     
     
       32. A joule-heated melting furnace for the inertization of radioactive substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls suitable for containing radioactive substances,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank,  
       a gas outlet of said gas bubbler,  
       said gas bubbler including a gas supply pipe, said gas supply pipe extending from above a level of a glass melt into the glass melt,  
       said gas supply pipe including a protective sleeve at the level of the glass melt with the protective sleeve being fixed to the gas supply pipe, and  
       an annular gap formed between said protective sleeve and said gas supply pipe.  
     
     
       33. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 32 , wherein said annular gap includes one of magnesium oxide powder and mullite. 
     
     
       34. A joule-heated melting furnace for the inertization of hazardous substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls, and  
       a gas bubbler introduced into said tank for supplying a gas into said tank and stirring the contents of said tank, said gas bubbler being connected to a power supply for use of the gas bubbler as an electrode in the tank.  
     
     
       35. A process to stir a glass melt containing hazardous substances in a melting furnace, said process comprising: 
       inserting a gas bubbler into the glass melt above a bottom wall of a tank containing the glass melt,  
       passing a gas into the gas bubbler,  
       introducing the gas into the glass melt through an orifice formed in a metal insert of the gas bubbler made of chromium, and  
       passing an electric current into the glass melt through the glass bubbler.  
     
     
       36. A joule-heated melting furnace for the inertization of radioactive substances by vitrification with glass forming chemicals, said furnace comprising: 
       a tank having a bottom wall and side walls suitable for containing radioactive substances,  
       a gas bubbler introduced into said tank above said bottom wall for supplying a gas into said tank and stirring the contents of said tank,  
       a gas outlet of said gas bubbler, and  
       said gas bubbler including a gas supply pipe, said gas supply pipe extending from above an upper level of a glass melt into the glass melt,  
       said gas supply pipe including a protective sleeve surrounding said gas supply pipe at the upper level of the glass melt with the protective sleeve being fixed to the gas supply pipe so that the protective sleeve extends above and below the upper level of the glass melt, said protective sleeve including metal.  
     
     
       37. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 19 , wherein a ceramic material is located in the annular gap. 
     
     
       38. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 37 , wherein said annular gap includes one of magnesium oxide powder and mullite. 
     
     
       39. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 36 , wherein said gas supply pipe is enclosed by said protective sleeve. 
     
     
       40. A joule-heated melting furnace for the inertization of radioactive substances as claimed in  claim 36 , wherein said metal is an alloy of chromium and nickel.